As μ increases, say, to values greater than 30, the Poisson distribution begins to be very similar to the normal with both a mean and variance of μ. Using this approximation, determine how many...

As μ increases, say, to values greater than 30, the Poisson distribution begins to be very similar to the normal with both a mean and variance of μ. Using this approximation, determine how many 911-operators are needed to ensure at most 5% busy signals if the mean number of emergency phone calls at any given time is 40.